The present invention relates to an electromechanical linear actuator.
In particular, the present invention relates to an electromechanical linear actuator comprising an electric motor with a rotary output shaft, and a straight-line output member.
Linear actuators of the aforementioned type are known to comprise an electric motor with a hollow shaft, designed to impart reciprocating straight-line motion to an output rod extending coaxially through the hollow shaft and connected to the same via a screw-nut-screw coupling.
Though perfectly functional in most respects, known linear actuators of the aforementioned type present a number of both economic and functional drawbacks, due to the hollow-shaft electric motors employed, which are invariably more cumbersome and expensive than the equivalent solid-shaft types.
A known method of overcoming the above drawbacks is to employ a standard solid-shaft motor on which the hollow shaft is located externally using a tubular shaft parallel to the output shaft of the motor and connected to the same via any type of parallel rotary shaft drive. Though relatively straightforward in terms of design, the above solution is extremely difficult to actually implement for achieving an actuator with a relatively high degree of precision and long working life.
Long working life of the actuator, in fact, is usually only obtainable by providing for relatively rigid support of the driven tubular shaft, so as to ensure substantially perfect parallelism between the tubular shaft and the output shaft of the motor. Such a solution, however, invariably results in the vibration produced by the motor being transmitted to the driven tubular shaft, and in impaired performance of the screw-nut-screw coupling.